Aluminum complexes incorporating symmetrical and asymmetrical tridentate pincer type pyrrolyl ligands: Synthesis, characterization and reactivity study

摘要

A series of aluminum complexes incorporating substituted symmetrical and asymmetrical tridentate pyrrolyl ligands are synthesized conveniently and the treatment of the derivatives with small organic molecules are analyzed. The reaction of lithiated [C_4H_2NH(2-CH_2NH ~tBu)(5-CH_2NR_1R_2)], where for 1, R_1 = R_2 = Me; 2, R_1 = H, R_2 = ~tBu, with AlCl3 in diethyl ether affords Al[C_ 4H_2N(2-CH_2NH~tBu)(5-CH_ 2NMe_2)]Cl_2 (3) and Al[C_4H_ 2N(2,5-CH_2NH~tBu)_2]Cl_2 (4), respectively, in high yields. Furthermore, subjecting 3 and 4 to reaction with one equiv. of LiNMePh in diethyl ether generates Al[C_4H_ 2N(2-CH_2NH~tBu)(5-CH_2NMe_ 2)][NMePh]Cl (5) and Al[C_4H_2N(2,5-CH_ 2NH~tBu)_2][NMePh]Cl (6), respectively, while eliminating one equiv. of LiCl. The reaction between compound 4 with two equiv. of LiO-Ph-4-Me in diethyl ether yields the aluminum di-phenoxide compound Al[C_4H_2N(2,5-CH_2NH~tBu)_ 2](O-Ph-4-Me)_2 (7) whereas the combination of 3 and two equiv. of LiNH~tBu, produces Al[C_4H_2N(2-CH_ 2N~tBu)(5-CH_2NMe_2)](NH~ tBu)(NH_2~ tBu) (8). Additionally, the mixing of 1 and one equiv. of AlMe_3 renders Al[C_4H_ 2N(2-CH_2NH~tBu)(5-CH_2NMe_ 2)]Me_2 (9). Adding one more equiv. of AlMe_3 with 9 affords {Al[C_4H_2N(2-CH_2NH~ tBu)(5-CH2NMe_2)AlMe_3]Me_ 2} (10), which can also be obtained by treating 1 with two equiv. of AlMe_3 directly. The treatment of 9 with one equiv. of 2,6-dimethylphenol in diethyl ether gives the aluminum alkoxide derivative, Al[C_4H_2N(2-CH_2NHtBu)(5-CH_ 2NMe_2)](O-C_6H_3-2,6-Me_ 2)Me (11). Furthermore, the reaction between 9 and one equiv. of 1-ethyl-1-phenyl ketene, initiates the aluminum dimethyl complex Al{C_ 4H_2N[2-CH_2CEtPh-C(O)-NH~tBu](5- CH_2NMe_2)}Me_2 (12) with a C-N bond breakage and a C-C bond formation. All the Al-derivatives are characterized by ~1H and ~(13)C NMR spectroscopy and the molecular structures are determined by single crystal X-ray diffractometry in solid state.